The first thing a DIY stair builder should learn is there are two different classes of stairs. The first class is a mill-made stair, which is usually fabricated in a mill shop and shipped to the job site as a kit, ready for assembly and installation. The second class, a carpenter-built stair, is just that — a stair built on site by a carpenter. This type of fabrication is less expensive and makes perfect sense for stairs that will be covered with carpet. A carpenter-built stair can be dressed up with a hardwood or paint-grade skirt board, and a simple wall-mounted railing is a popular option to complete either type of stair. When building a stair, functionality is the most important consideration. Extreme accuracy must be used for a safe design. Before beginning construction, you should consult not only the national building-code requirements, but also the local building- code requirements. Some municipalities have stricter codes than others, and checking first will eliminate the need to rebuild later. The construction materials that you use will dictate the outcome of your finished product, and quality materials will produce a quality job. Don’t mistakenly think that if you plan to cover the material with carpet, the quality of construction materials doesn’t matter; it does. A lower grade of material that contains knots and voids may cause the stair framing to crack at a later date. Most lumberyards carry stock used specifically for the construction of stairs. LAYOUTS AND CALCULATIONS After you have determined the proper codes to follow for your municipality, grab a pencil and commit your plans to paper. Sketch a rough blueprint of your staircase. For the purpose of this example, this proj- ect will be a straight stair. The building code we are implementing for this project requires a maximum riser height of 7-3/4 inches and tread run of no less than 10 inches. First, determine the size of your stairwell, making sure to allow for the proper head- room to accommodate the stairs. Headroom is very important; you need to be able to ascend and descend the stair safely without smacking your forehead. Many a stair has been torn out due to incorrect calculation of this item before the stair was built and installed. For this example, the nosing will be a standard 1-1/4 inch, the tread run will be 10 inches each, and the headroom will be 6 ft., 8 inches. Assuming the distance from one finished floor to the other (total rise) measures 118 inches, find out the number of risers needed by dividing the total finish rise by 7. 5. The result- ing number equals the number of risers. Then divide that number into the total finish rise.
By Doug Adams